Theoretical calculations of K-edge absorption spectra in warm dense Al

Theoretical calculations of the shape of an absorption edge in a warm dense simple material such Al are described. The calculations include the XAFS (x-ray absorption fine structure) features above the edge. The shape of these modulations relates to the atomic spatial distribution and to the electronic density of states (DOS) in the continuum. The underlying warm dense plasma model is based on a density-functional neutral pseudoatom approach which gives the radial distribution function (RDF) and the electron density around one specific site. Combined with a full multiple-scattering (MS) approach giving the final free wavefunction in a photoionization process, the model is used to predict the shape of photoabsorption K edges over a range of compression ratios from 0.5 to 3 and temperatures from 0.1 to 10 eV. It is found that XAFS structures are intense enough to be observable for densities of the order of (and above) the solid density and that dynamic or static absorption spectroscopy measurements could provide interesting information on the warm dense matter regime